An Evolution in Construction

APRIL 2010CONSTRUCTION AND THE BUILT ENVIRONMENT

“like Darwinian novation, it is therefore an evolutionary process that robotics will become commonplace in construction methods”

Ross Overfield-Collins


Evolution in Construction An Exploratory Review of Mega Scale Rapid Prototyping

Ross Overfield-ColliQV8QLYHUVLW\�RI�:HVWPLQVWHU��Z��'HSW��&RQVWUXFWLRQ�DQG�WKH�%XLOW�(QYLURQPHQW:RUG�&RXQW��


“I hereby declare that this dissertation is as a result of my own independent endeavours and investigation, except where I have indicated my indebtedness to other sources. I further declare that this dissertation has not been accepted in substance for any other degree, nor is it being submitted currently for any other degree. Ross Overfield-Collins 18th April 2010

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Acknowledgements

It is with great appreciation that I would like to thank Enrico Dini of D-Shape, Dr.

Behrokh Khoshnevis of Contour Crafting and all those who contributed from

Loughborough University for their valuable information within this project.

My special thanks to my supervisor, Dr. Edin Moosavi for all his help and guidance

throughout this work, has steered me onto the correct path many a time. I am also

grateful to Terry Wohler and Wohler’s Associates for their patience, expertise and

product sector knowledge, without which I would not have been able to produce this.

And finally I would like to thank all of those family and friends who read and re-read this

project; who encouraged me and gave support throughout the whole course.

I am eternally grateful.

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iv.

list of tables

list of figures

What is Rapid Prototyping?

The Ideology

Reason for Aims and Limitations of Research

quality

ggeometric freedom

mass customisation

materials

costs

end users

Aim

Objectives

MethodoloMethodology

Structure of the Dissertation

The state-of-the-art

the use of robotics in other industries

robotics in construction

State-of-the-art-RP technology

materials used in rapid prototyping

the impact the impact rapid prototyping has had on the industry

Research into Printing a Building

1.11.21.31.3.11.3.21.3.31.3.41.3.41.3.51.3.61.41.5

2.12.2

3.13.13.1.13.1.23.23.2.13.2.23.3

4

10

33

13

5

67

77

6

8

899

1515

1516

1819

20

1112

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introduction 1

research method 2

literature review 3

Case study: university of southern california

Case study: freeform engineering

Case study: d-shape

interview with enrico dini

Drivers For Change

Sustsainablility

IInvestment

investment in the construction industry

investment in mega scale RP

Software

Designing the Future

archineering

Materials, Methods and Integration

integintegrating two materials

the operating mechanisms

Acting on Drivers For Change

quality-cost correlation

speed

quality

design freedom

TThe Future of Mega Scale RP in Construction

Bibliography

Appendix

4.14.24.34.3.1

5.15.25.35.35.3.15.3.25.45.55.5.15.65.6.15.6.15.6.25.75.7.15.7.25.7.35.7.45.85.8

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5 discussion

4 case studies

6 conclusion:

the direction this technology is heading


List of Tables

3.1. Summary of Rapid Manufacturing Techniques 3.2. Summary of Rapid Manufacturing Materials 4.1. Possibilities for Processes for Creating FreeForm Structures (Courtesy of Loughborough University)

List of Figures

1.1. Illustrated geometrical freeform (image courtesy of InGlass) 2.1. Research methodology, Soft Systems Model (modified from Checkland, 1990) 3.1. Non-Cartesian welding robot (image courtesy of Motorman inc.) 3.2. Corus automation (image courtesy of Corus Group) 3.3. Illustrated 3D process (image courtesy of R.A. Buswell) 4.1. Illustrated Contour Crafting process (image courtesy of CRAFT) 4.2. Estimated research schedule for Contour Crafting (image courtesy of CRAFT) 4.3. Contour Crafting wall constructed in collaboration with Caerpillar (i mage courtesy of CRAFT) 4.4. Schematic representation of the CC trowel operation (image courtesy of Kwon, 2002) 4.5. Reinforcement within the extrudate material (image courtesy of Kwon, 2002) 4.8. Panels designed and printed in conjunction with FreeForm construction (image courtesy of Loughborough University) 4.7. Multi-service trunking (image courtesy of I3CON) 4.8. Drawings, details and workshop images of Villla Rocce (images courtesy of Enrico Dini and Faan Studios) 4.9. Inorganic binder in operation (image courtesy of Enrico Dini) 4.10. Hypodermic needle illustrating the surface tension in a droplet (image courtesy of WhiteNeedles.co.uk) 5.1. Free-Electricity generator (image courtesy of Innovative Technologies Ltd.) 5.2. Eda Yetis’ Hurricane House, produced using Selective Laser Sintering 5.3. Artists impression of topological optimisation (image courtesy of Loughborough University) 5.4. Fused Deposition process (images courtesy of Trumpf and Hopkinson, 2006) 5.5. Artist impression of a multi-axis robotic arm using Contour Crafting (image courtesy of CRAFT) 5.6. Hexapod system (image courtesy of NIST) 5.7. Dimensional accuracy graph (image courtesy of Urbanska-Gaewska, 2008) 5.8. Cost comparison (courtesy of R.A. Buswell) 5.9. Speed comparison (courtesy of R.A. Buswell)

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1. Introduction: Background to the Topic

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7.


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9.

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RESEARCH METHOD“This“This research is primarily focused on investigating variables, through which hypotheses may be generated, for future research. It could also be categorized alongside predictive types of research howeverhowever the empirical approach required to achieve the objectives requires a more exploratory review of the data.”

freeform construction

semi-solid pastes

3D printing


Fig.2.1: The Modeling Process (developed from Taha 1971; Checkland 1990)

2. Research Method

2.1. Methodology

This research is primarily focused on investigating variables, through which hypotheses

may be generated, for future research. It could also be categorized alongside predictive

types of research however the empirical approach needed to achieve the objectives

requires a more exploratory review of the data.

The theoretical soft systems model (SSM, Fig.2.1) of Checkland and Scholes (1990) will

loosely be adopted whereby both theory and practice will be assessed separately but

combined in a formulative and summaritive evaluation of the findings.

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To achieve the research objective a combination of research methods was adopted.

Methods include interviews, a desk study, and case study analysis.

Both the desktop study and case study analysis use a positvism approach, whereby

facts and causality are the primary focus of the documents (Fellows, 2008), these

sources can provide the insight into the ideas behind mega scale rapid prototyping.

Case studies can also be interpretivist, whereas interviews are, predominantly the latter,

therefore all three approaches to the research should provide a well-rounded and

unbiased view of the subject.

Similarly both qualitative and quantative approaches will be sought for this research.

Qualitative being that of descriptive based interpretation, of people’s views around the

specific subject matter; but also deciphering any bias of that information, to develop a

coherent and comprehensive iteration. It should be noted that by undertaking

unstructured interviews from a wide spectrum of participant’s perspectives an in-depth

view of the subject was ascertained, which will latterly be communicated as part of this

study.

Quantative data is the collection of previous work and theories; this systematic analysis,

will allow, according to Morse (1994) a saturation of information whereby a formulative

and summaritive assessment can be drawn.

2.2. Structure of the Dissertation

The following chapters will address the state-of-the-art technologies associated with

Rapid Prototyping and Rapid Manufacture. The literature review in particular will

highlight the research undertaken by specialist groups with an interest in mega scale

construction, upon which, will provide a precedent for the processes, shown by the case

studies in chapter 4.

Minutes of the numerous meetings will not be included herein (with the exception of D-

Shape analysis), however the findings will be discussed in the discussion section

(chapter 5), along with the phenomena found by evaluating the comparable case studies

of those research groups actively interested in mega scale RP construction. These will

thence be summarised (chapter 6) and presented in a clear and logical manner, to

highlight the clear direction this technology is advancing towards.

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ReLiterature

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Fig. 3.1: The 7-Axis, VA1400 Arc welding robot can offer improved access into extremely tight spaces (Image courtesy of Motoman Inc.)

3. Literature Review

3.1. The State-Of-The-Art

State of the art is defined in the Dictionary of the English Language (2000) as being “the

highest level of development, as of a device, technique, or scientific field, achieved at a

particular time”. In relation to Rapid Manufacture it would be the most recent processes

and technology known to be in existence at present.

3.1.1. The Use of Robotics in Other Industries

In other industries, robots are commonplace to produce complex and intricate tasks, for

instance the car manufacturing industry has used robots to weld, maneuver, machine

and process components for decades.

They recognised early on that automated methods

can often achieve a finish which is higher in quality;

consistently producing results faster, more efficiently,

more accurately and without stopping (Expo, 2009).

Consequently complimenting any weaknesses

humans may face on a manufacturing line. This is

particularly true of the engineering industry where

robotic and Computer Numeric Control (CNC)

machines are now common place, producing engine

blocks, rig drilling equipment, aeronautic parts etc.

using simple 3-axis machines (x,y,z directional planes), up to 7-axis robotic arms

(Fig.3.1).

3.1.2. Robotics in Construction

The attractive prospect of efficiency, and reduced energy consumption has not

bypassed the construction industry. It is now with great virility and regularity on large

construction sites to see wall crawlers fixing facades to a frame, lifting mechanisms and

generally more mechanised operations. Yet with more on site robotics being used to

increase production, it is off-site manufacture that is dominating Modern Methods of

Construction (MMC). With many companies being able to produce accurate, pre-

designed, pre-fabricated sections of building that can be erected in a matter of days.

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This reduces on-site costs, but drastically increases costs off-site during the design

stages (Totten, 2008).

Corus, the leading British steel manufacturer uses

robotic welders to fabricate its steel sections

(Fig.3.2) which simply bolt together on-site,

similarly Huuf houses use a robotic welding and

machining off-site. However timber manufactured

panels can also be produced using off-site

manufacture; Kingspan has produced structurally

insulated panels (SIPs) with great effect in Britain’s

first zero carbon house, the aptly named

‘Lighthouse’ in BRE’s innovation park.

The BRE have stated that by using factory automation these high performing buildings

were only possible because of the highly automated processes used in production. So

like Darwinian novation, it is therefore proposed that like an evolutionary process;

robotics will become commonplace in construction methods, and Rapid Prototyping may

have the potential to cause this paradigm shift towards automated construction.

3.2. State-Of-The-Art RP Technology

Commercial additive fabrication emerged in 1987 with the introduction of the SLA-1

stereolithography (SLA) machine by 3D Systems, which set the precedence for making

physical 3D models from computer generated models (3D-Systems, 2009). Today there

are numerous methods to transform a computer aided model into a reality, including

material reducing methods like CNC machining, but none have the flexibility and

geometrical freedom of material additive methods (Jacobs, 1992).

Figure 3.3 shows a typical 3D printing method, step-by-step, it highlights the necessity to

‘slice’ the 3 dimensional model, back into 2.5 dimensions; two and a half dimensions are

the result of the minimum thickness that a layer can produce, it is almost in limbo, as it is

too narrow to be useful as an object yet it is still has a physical dimension, albeit on a

micro level. Then sending the individual slices to the Computer-Aided Manufacturing

Fig. 3.2 Automation at the Shotton Works; Corus Factory (Construction Dept.) (images courtesy of Corus Group).

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(CAM) software for analysing and registering the specific extrusion/sintering path of

each layer.


Fig. 3.3: Representation of the 3D Printing Process in Stages (Image courtesy of R.A Buswell et al., Freeform Construction: Mega-scale Rapid Manufacturing for Construction)

By far the most used technology of this kind and rapid manufacture of late is

stereolithography and it variants. Above is the process 3D printing, often wrongly classified

as being the method which encompasses all the processes involved in additive fabrication, it

is classified by Wholers Associates as being a completely different system altogether

(Wohlers, 2008), separate from other major processes that include; Fused Deposition

Modeling; Selective Laser Sintering; Aerosol Jetting and Semi-Solid Freeform Construction,

many of which can be seen in an overview of all the current processes in table 3.1.

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In a recent interview, Terry Wohlers also goes on to describe that high precision

manufacturing is indispensible for using these techniques commercially (2010). It is

obvious to point out that by reducing the layer thickness, construction time would

increase, so it would be best to selectively use higher resolution methods where

applicable i.e. for the smooth interior surface of service pipes.

In order to print a building from the ground up, or similar, it would also be essential to

utilise different materials. As different materials harbor different properties it is

necessary to therefore choose the right material and hence the method of printing for

producing such a structure.

3.2.1. Materials Used in Rapid Prototyping

Construction on site has specific needs, the materials need to be dense enough to not

be affected by climatic conditions, but materials in Rapid Prototyping may not specifically

need to be so heavy and therefore can be housed in a cabinet as a powder.

More often than not materials are spread across a printing platform and then fused

together through various methods, depending on the material.

Plastics can be either fused using binders or light rays. Binders may solidify the polymer

powders using liquid chemicals (glue) to provide the thermal reaction necessary to bond

the molecules, and is deemed as a highly cost effective method of prototyping. But

whereas lasers which melt a range of plastics including, polycarbonate, ABS and a

nylon-silica powder to create a durable and resistant product; light reactive polymers,

used during stereolithography, have a distinct disadvantage that the materials have a

natural tendency to decompose at an accelerated rate in natural light.

Metals can be fused in a similar fashion, by using very powerful lasers, the metallic

powders are welded, but some powder layers may not always be distributed evenly

which can form voids in the metals, and where there are voids there is an integrated

weakness which would not represent a comparable cast piece. But to overcome such a

problem parts may be vacuum cast (EBM) to eliminate any air gaps in the material,

hence provide a material that is fully dense and suitable for applications such as formula

one engine components.

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To summarise the following materials can be associated with their respective printing

technique:

3.2.2. The Impact Rapid Prototyping Has Had on the Industry

Since the introduction of the first 3D printer its popularity has steadily grown. Initially a

very expensive process which has now become more accessible than ever with more

machines being produced and sold globally. Consequently the cost to buy one of these

machines has rapidly decreased; nowadays a rapid prototyping machine is typically

valued at £6,000 - £15,000 (Grenda, Castle Island, 2008), making it an ideal tool for

architects to model their ideas physically, giving their client something they can see and

touch. But it also provides a useful insight into the possibilities of making complex

structures (albeit in miniature) in one single print.

The finished result can express visually what the architect envisaged. In modern

design trends; architects like Zaha Hadid et al. are producing elaborate and

complex designs which are easily produced whilst modeling virtually, yet in reality,

possess curvatures and visions which are difficult and very expensive to

manufacture, unlike their printed models.

3.3. Research Into Printing A Building

Aside from the vast resources detailing rapid prototyping and its derivatives, there is very

little primary information that examines research into generic construction using rapid

prototyping methods. As such many of the secondary sources used were done so with an

err on the side of caution, as it is unclear their bias toward one system or another, and

because much of the information was gathered from the internet (a source easily tainted),

these biases were judged and merited accordingly.

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Of those primary sources to note were past papers and doctrines from; The University of

Southern California (USC); University of Loughborough (UoL); and, the Royal Melbourne

Institute of Technology (RMIT). Although the latter offers only one source of information on

research in this field thus far.

The other major research group is, in fact, not a group at all, but a private company (D-

shape), who have pioneered a different method from the prior three. There were no direct

primary sources of information on this particular method, which purported data collection via

interviews and emails direct to the founder.

The industry has now widely accepted off-site manufacturing, and is seemingly well verse in

the subject matter, yet the opposite could be said for Rapid Prototyping and because the

nature of this research directly addresses a state-of-the-art process it was necessary to

examine a wide spectrum of people. Of those who were contacted it was usually necessary

to personally inform prior to obtaining viewpoints on the subject matter. It must be noted that

the majority of the information was from past papers and people involved with the research

in question. As those people are the most informed, however a small selection of industry

officials were also accounted for, as they will be the most likely to use the systems described

herein.

Due care was taken to ensure that participants were fully aware of the topical nature and

that they fully consented to the use of any quotes, information and images that are

presented. No waiver was signed however at the beginning of any recorded interview or

written statement it was noted that the statements made were voluntary and should cause

no harm to their professional status or otherwise.

The research already undertaken will be summarised as follows, yet a detailed analysis of

Contour Crafting (USC), D-Shape and Freeform Engineering (UoL) Processes will be

described in the next chapter. Information from RMIT was unfortunately unobtainable at the

time of this research, however their interest in the subject matter must be noted.

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Fig. 4.1 & 4.2: The process & the estimated research schedule of Contour Crafting, including the check/hold points (Image Courtesy of CRAFT).

4.1. Case Study: University of Southern California

Much of the research undertaken at USC is headed by Dr. Behrokh Khoshnevis at the

Center for Rapid Automated Fabrication Technologies (CRAFT). The system (Contour

Crafting) is a layered additive fabrication technology, where both off-site and on-site

fabrication is maximised, and coordinated in one operation; by extruding concrete, or a

similar quick setting paste for the main substructure, whilst placing beams and lintels

across areas where spans are required. The primary aim of this research is to print a

building in a day, in a single run, with embedded conduits for electrical, plumbing and

air-conditioning (Lane, 2004) (See Fig.4.1).

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Fig. 4.3 A partnering initiative between Caterpillar & USC has meant a 6ft wall has been printed using contour crafting, with three nozzles (and two exterior trowels) working in unison. Note the same material is used throughout (Image courtesy of CRAFT).

Their research programme is summarised in figure 4.2; it highlights the check and hold

points (AKA milestones) of the research, and shows three key areas which CRAFT

deem necessary to build a house in one operation. These being Materials and

fabrication of said materials; Modular components; robotic assembly; and, the software

development that will allow an integration of these past two processes. But moreover

will enhance logistics of material delivery and similarly modular delivery.

Despite a vast knowledge of Viterbi

algorithms and past RP computer

programmes, “much of the software didn’t

exist”, says Paul Rosenbloom (USC, 2004)

and work was consequently focused on the

co-ordination software for multiple nozzles to

work in the same operation. This can now be

seen with the development of the wall, which

was produced with aid from caterpillar funding

and engineering expertise, where the biggest

success is in regard to a ‘printed’ six-foot tall

concrete wall section in one motion.

Previously it was difficult to sustain a

continuous extrusion path without material

subsidence, but after teaming up with USG

Corporation, a quick drying cement was

developed which could be built in 13cm increments with hourly delays to control lateral

stability and alleviate buckling. However this rate could be reduced still, depending on

the amount of accelerant within the cementuous paste (Khoshnevis, 2006).

Each successive layer is extruded and smoothed in 25mm, which is determined from the

distance between the bottom of the trowel and the top of the deposited material. This

can ultimately be adjusted, however after detailed research from Hongkyu Kwon (2002),

it was proven that this was the optimum for the thick and viscous material. He also

concluded (without disclosed particulars), that the pressure should be great enough to

allow sufficient fusion and plastic flow onto the subservient layer, yet should be low

enough to avoid distortion the part.

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Fig. 4.4: A Schematic representation of the Contour Crafting process under sub-optimal conditions (Image courtesy of Kwon, 2002).

Fig. 4.5: Laying hollow sections through Contour Crafting. During, before and after shots of the extrudate throughout the deposition process (Image courtesy of Kwon, 2002).

If the uniform flow was too little, and the orifice

was oval and not square in profile, the

deposited material would not be squeezed

against the side of the trowel and would hence

produce a stepped effect, rather than the

desired smooth surface finish (Fig. 4.4).

This vital doctrine also explained the need for

reinforcement of the material. Innovative solutions were provided by forcing the

extrudate through the nozzle with a centralized mandrel, which effectively left a layer

with a central void (Fig.4.5). It was mentioned that this void could be filled with a

secondary material, one which has now become apparent is the nanoparticle metallic

pastes (Ishibashi, 2004). Which are of such a high density they could perform the role of

rebar within this deposited concrete. Alternatively, CRAFT examined the application of

placing reinforcement as coils, on top of the extrudate, which is then covered as

successive layers are deposited on top of the former.

Amidst the current research, particular applications include low cost housing, emergency

housing (for stricken areas), social, and even lunar automated construction. The vision of

the research is quite interesting, previous laboratory tests showed promising rates of 200m2

could be built in 24 hours, which far out performs any current construction methods (typically

6 months+ for the same size). In addition it was mentioned that resulting from the shear

speed of the construction and moreover the drastic reduction of labour, projections indicate

production costs will be around one fifth of conventional construction methods (Mudholker,

2006).

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In accordance with the Contour Crafting pick-and-place modular element, German

Construction Products giant Degussa, has also partnered with CC to provide their

solution to segmentally install components such as plumbing and electrical parts during

the layered process (voids are left in the structure to allow placement of the parts). One

such solution is the adoption of pre-soldered pipe connections, both to the male and

female ends, which are placed and heated in the same operation, by a robotic gripper

arm. Other modular elements include standard, stressed beams, yet of note are the

electrical and communication wiring, which are similar to industrial bus-bars, but are

connected by placing one electrical module on top of another, using robotic automation

for that same purpose.

These can also be placed in the conduits provided by the programmed blank areas, but

where these are not provided, Degussa has suggested implanting sensors that measure

the performance of the building. In particular reference to heat sound or stress levels,

therefore integrating a smart building system which can be monitored by its occupants,

or a system which in the future, may provide the controlling mechanisms for active

HVAC and entertainment assemblies.

4.2. Case Study: Freeform Engineering

Much of the research from the University of Loughborough has been looking at the

application of off-site RP in the construction industry, for near-term commercial

deployment. However this has been integrated with more long-term strategies and in

particular the automation of wet trades has been given a great deal of attention. Much

the same as Contour Crafting (but without the multiple trowels smoothing the surface),

However the Freeform Engineering research facility was given a £1.2m grant (EPSRC,

2007) to further develop and demonstrate a mega scale additive fabrication method that

can print building components, and to develop new processes and materials which will

drive the construction industry forward.

It has been mentioned that retrofit eco-technologies actually encourages greater

embodied energy for the whole structure (Miller, 2008), but FreeForm believe that

energy capture can only take place at the design stage, whereby green technology is

designed in, or integrated into the fabric of the structure (2009).

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Fig. 4.6: Panel systems designed by the Freeform Engineering Department maximise the design and prototyping capabilities of RP. Te top image depicts panels which are designed to reduce thermal conductivity, and the images below show a panel (front and back) that reduces acoustic noise (Images courtesy of IMCRC).

This has led to the feasibility study of integrating more functions into less form, this is a

similar concept to Contour Crafting, but where CC has yet to develop these ideas

further, Loughborough have actively researched the capabilities of printing acoustically

designed panels and similarly, panels that minimise thermal conductivity (Fig.4.6).

All three of these panels were produced

using a Z-Corporation 3-D Printer and

gypsum powder, which is a readily

available source, however one could argue

that this chalky mineral is also limited, and

consequently is not necessarily sustainable

for long-term use.

Additionally Buswell et al. (2007) showed

that by extrapolating the performance

characteristics of the 3-D printer and the

associated material; a hypothetical mega

scale printer would be similar in build time

to traditional methods (Brick & Block).

Although this may now be more in favour of

RP with the High Speed Sintering system

which is said to be 10 times faster than

previous methods (Hopkinson N. , 2009).

Additionally the process may also yield

slightly lower material costs, resulting from the single material construction and reduction

in assembly complexity. But, where the distinct benefit arose was in value added

operations, much like the afore panelised construction. It was noted that by using the

same material, recycling of the building materials would be far easier, plus where there

are highly serviced walls, the printed structure would allow for such designs to

accommodate these services in addition to a thermally rewarding performance (a lesser

k-value than aerated concrete).

Yet by examining the acoustic panel Godbold (2007) found that he was in fact restricted

in his designs, therefore dissolving the perceived advantage of geometrical freedom. He

showed this by demonstrating that Helmholt resonating absorbers use a small orifice

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opening out into a void, but this was not possible to reproduce using powder based RP. As

the support material, or un-sintered layers would not be accessible for removal. Thus

concluding that the process, in this case, restricted the design of such devises. In addition it

was demonstrated that there was a vested conflict between the rate at which material was

deposited and the resolution required in order to produce clear definition and resolution of

the printed structure (Hopkinson N. &., 2006). Although faster printing is economically more

rewarding and ensues less shrinkage occurs, it often produces components with poor edge

definition. Vice versa, if slower printing takes place, there is an increase in mechanical

strength (bonds are more frequent and binding), yet this time it is the accuracy that suffers,

resulting from higher material shrinkage, and similarly this is done at a “cost definition”.

Nevertheless it is an interesting approach to printing a building. The part consolidation

associated with this panelised system is much like modular methods, yet unlike modules or

even structural panels, these printed panels exhibit greater topological freedom and in use of

integrated functions could prove a cost effective method for producing large building

components.

In Buswell’s paper, Mega Scale Rapid Manufacturing for Construction (2007) he compared

rapid manufacture to both traditional and off-site technologies, amidst which he assembled a

group of 13 organisations and academia alike, and asked the question; “If you could have a

freeform machine today, what would you use it for?

The response is summarised in table 4.1. It highlights six key areas of the building

elements, however one might add into the table foundations as well, as a leveled base to

build upon, is naturally a high priority.

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Fig. 4.7: Multi-service trunking, could incorporate service pipes, with optics and electrical routes, all housed, yet segregated, in the same casing (Images courtesy of I3CON).

From this invaluable insight, it was concluded

that the construction industry, in the near

future at least, would find RP beneficial

where complex forms are requisite to the

design and in particular the integration of

component and systems integration. This

latter point directly addresses the

combination of panels and its subsequent

internal services, which could be the

founding reason why Freeform has led its

research in a different direction from Contour

crafting, and has subsequently produced

innovations such as multi-service trunking,

which has emerged as a distinct viable

possibility for future use, but moreover its

production was only realised through rapid manufacture (see fig.4.7). The driver in this

case is not a personal vision, as per Dr. Behrokh Khoshnevis, but a conglomerate of the

people who may actually use the system.

It was also noted that such new technologies could be met with barriers, often deemed

as barriers to innovation (Manseau, 2005). Which include areas such as political will,

the business efficacy and perhaps more relevant, the ability to conform to building

legislation (Soar R. &., 2006). This could be said for global legislation not only national

governments, thus a system should be suitably adaptable to all global demands, should

it become commercially viable.

Biomimicry

However perhaps some of the most interesting research was carried out by Soar, who

recently left the faculty, but left in legacy, his ideas of biomimicry and living buildings

(Soar R. &., 2008). Much of which was based on his studies of termite mounds, which

led to the innovative passive cooling systems in buildings like the Swiss Re, but he

demonstrated that by using RP varying thermal masses and thermal resistances are a

possibility and cannot be easily replicated through other production methods, this can be

achieved topographically, or by altering the materials. Yet in the Adaptable Futures

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programme, the initiative fronted by acronym ATKINS, shows that although this is

theoretically possible, the potential to mix/grade material boundaries is still unfounded,

as it cannot be represented by any CAD system in operation today (Rapid

Manufacturing a Low Carbon Footprint, 2008).

A similarly conceptual idea was brought about by the same author; Soar stated that

house printing machines will be made up of swarms of tiny robots which behave

independently, yet work in co-ordination with other robots in a controlled building regime,

seen in his study of termites.

He realises, “this is the rest of my life’s work, and possibly my children’s as well”

(Pimlott, 2009), but this idea has been backed up by several bloggers on the contour

crafting website (Contour Crafting Blogspot, 2006). One to mention is

Civilisation_in_2100?, who states in the same vein, that small robots could crawl around

a skeleton structure i.e. a wired frame, and ‘work 24/7’ at a relatively leisurely pace,

conversely communicating to a centralised computer, which ultimately results in greater

construction yield, from little energy expenditure.

This is similarly a scope, which ATKINS feels necessary to research, as part of their

£2.9m grant is dedicated for Automated biometric design integration, where novel

software algorithms will permit the automated design of several geometrical elements.

But where this research looks toward the near-future, it encompasses software

development of waste minimisation during the construction phase. This includes tooling

paths that can optimise the latter; digital supply chains; and the reduction of greenhouse

gas emissions over the whole product life-cycle. Hague, a professor at the university

stated, “The benefits of the technology for consumers, industry and the environment is

quite staggering. For example, a 50 per cent weight saving in components will mean

much less material/energy is needed, which means less CO2 is released into the

atmosphere. Additionally, a reduction in wastage at the manufacturing stage and the

ability to create parts where and when they are needed, rather than at a factory

hundreds of miles away, will also help reduce costs and the environmental impact.”

As such, by engineering the components correctly, gains could be made in regard to

sustainability, a hotly pursued governmental agenda, and components which are “super

light, super strong and functional” may become a reality (IMCRC, 2009).

30.


Fig. 4.8: Conceptual drawings, Working Details and the printed elements of Villa Rocce (Images courtesy of Enrico Dini and Faan Ltd.).

Fig. 4.9: Inorganic binder being deposited over the print-bed. Note the size of the stream and the bead which results from the process (Images courtesy of Enrico Dini and Faan Ltd.).

4.3. Case Study: D-Shape

After initial talks with Enrico Dini, it became clear of his intentions to print a complete

structure using his technique. Where the economic downturn has affected Contour

Crafting’s research and development budget (Pimlott, 2009), D-shape is a privately

funded operation and consequently is only limited by the budget of Monolite Ltd. Further

still this has enabled D-Shape to follow through with its ambitions, to be the first of the

three methods to print a self-supported structure, the Radiolaria. Moreover alongside

Architect James Gardiner, of Faan Studio, construction of the first printed house, the

Villa Rocce House (fig. 4.8) in Porto Redondo, Sardinia has already started and is due to

be completed late 2010.

The system is much like methods shown in 3DP, or 3D Printing, and uses similar

algorithms from the 3D printing processes to manipulate 300 nozzles, emitting the binder

onto the substrate.

Magnesium oxide powder (the catalyst) is

dispersed amongst the grains of sand, which

is deposited and smoothed in 5-10mm thick

layers. This catalyst is then activated as the

rig passes over the sand bed and selectively

drops a chloride binding liquid to form a

viscous set (value between 1x10~3 Nsm-1 and

2x10'3 Nsm-1 (Dini, WO/2009/037550, 2009))

at the point of contact (fig.4.9).

Preliminary tests used a premixed binder, which he then found to be troublesome as the

1mm aperture of the nozzles quickly became blocked. In order to alleviate this he

premixed the binder with the sand, as previously mentioned. The machine now

31.


re-circulates the binder when the printer is not in operation, as this eliminates any

stagnation or desalinisation of the solution.

After the rig has made the necessary number of sweeps across the printing deck, the

unbound granular material is removed, revealing the printed structure. Of which has a

25dpi resolution over a 6x6m printing area, up to 3m in height. However this height is

rarely necessary, as the most efficient use of the printer (and material) is to fill the whole

area of the printer deck with low-rise segmented pieces, which optimises the use of the

machine, but ultimately speeds the process up, and conversely these segments can

later be glued together using the same binder and catalyst (Dini, Interview 11/12/09,

2009). It may be easier in the long run to print an entire building, or full height

components, but this will not maximise the use of the machine, nevertheless architects

and engineers still desire a machine that will build the structural entirety, as Xavier

Dekeste of Foster and Partners states, “the idea is to press print and just do it”, therefore

simplifying their role as a contractual supervisor and enabling them to concentrate on

their primary function, design.

On the other hand, one major advantage of this method is the ability to produce

synthetic marble-like stone, not over a period of decades, but hours. It takes one day to

print 150mm of stone (with operation maximised at 300mm) for a 24hr period, and

comparing this to the other methods shown in this paper, this is by far the slowest and

most privative process. During a one-to-one interview, Enrico Dini was quite open to

admit the process is relatively slow, partly factorial of the human recalibration upon

every layer, he states quite jovially, “there is a certain dumbness to the binary logic”, but

it’s also the most sustainable method out of the three. Its inorganic compound does not

contain any hydrocarbons, but additionally the sand, which is the dominant material in

the granular mix, is widely available globally.

And, due to the microcrystalline structure, it possess mineral-like qualities, which during

testing have shown significant hardness and high tensile strengths over and above that

of concrete (the primary material of CC and Freeform).

32.


Fig. 4.10: A Hypodermic needle, illustrating the formation of a large droplet size from a small aperture (Image courtesy of WhiteNeedles.co.uk).

Yet the process itself limits the potential of this

method. It could be seen in fig. 4.9 that the streams

ejected from the nozzles were of a large diameter,

which will unquestionably affect the final resolution.

Although 25dpi was stated, the printed parts require

extensive work, removing the unbound mixture,

beating off the recalcitrant parts (Abrahams, 2010),

and then sanding the exterior. This post processing

seems illogical when the objective of RP is to

deliver a working product as soon as it is printed; however because of the scale of the

operation these limitations are exaggerated.

One such limitation that contributes to this problem is due to the excessive ejection of

the binder from the on-off calibration, and similarly the nozzle heads are only 1mm in

diameter, yet they eject a 5mm wide stream as a result of the surface tension from the

solution at the tip of the nozzle. This is easily demonstrated by examining a hypodermic

needle when little pressure is applied to the plunger, small droplets appear far greater

than the head of the syringe itself (fig. 4.10). Moreover Prof. Mark Burry stated that

when the drops form as a solid, the binder naturally spreads linearly when it comes into

contact with the compound (SmartGeometry Day 2: Public Symposium and Reception ,

2010), and when the roller flattens the successive layer, which is designed to increase

the density of the material, further compresses the previous layers which exaggerates

the previous inaccuracies; consequentially a designed 5mm bead is compressed to an

approximate diameter of 10mm. This is well documented and during our interview

Enrico Dini (2009) mentioned that as a result of this process, an object, i.e. a pipe with a

designed internal diameter of 80mm could end up with an internal diameter of no greater

than 50mm.

This can be compensated during the design stages, however using modern methods of

construction as a precedent, in particular modular units, construction operatives and

designers often prefer precise methods (Corus, 2007), and were primarily attracted to

RP in the first instance because these processes offer a greater design freedom, with

the capability to produce accurate buildings (Schumacher, 2004) and ease of part

integration.

33.


Yet designing, ordering and retrofitting of windows and doors is still a necessity with this

approach, as the method is thus far, incapable of producing a building with a high

enough resolution to incorporate other elements, per Freeform. However it can be seen

from fig. 4.8 that conduits can be printed (Dini, Interview 11/12/09, 2009) as part of the

structure, so by optimising the structural element, internal geometry has proven to

reduce the materials whilst effectively improving the strength through load distribution.

And, beneficially, this house has also shown that hidden services could be integrated

during the physical erection of the components on-site (Gardiner, 2010).

4.3.1.Interview with Enrico Dini

During the interview with Enrico Dini, it was put to him that this method is not necessarily

the most accurate system with regard to edge definition etc. He continued to mention

that he is the solitary financier of this project, but interestingly he has looked into lunar

construction with this method, much the same as Contour Crafting, but where CC has

been given research grants from NASA, Enrico Dini has collaborated with the European

Space Agency, and in particular the Aurora Programme, which has led to a research

contract between these partners, plus the likes of Lord Foster (Foster and Partners) to

provide the design.

The main issue to improve the system is funding of governmental proportions. Bearing

in mind this is a two-man project up until now, Enrico claims it would take close to 20

staff for materials development, 20 staff for chemicals, 40 staff working on the machine

and a further 20 developing the software, totaling an approximate 100 extra staff

required to make this system commercially viable for the mass market. However

learning and development could be made through lots of smaller, independent parties,

and this seems to be the direction Enrico is heading, as part of the Architectural

Associations remit is to install a version of his machine in the Metropolitan University,

London. They themselves will be able to concentrate academic studies on the

apparatus, and will be able to offer new solutions and processes to the technology,

much the same as Contour Crafting, and Freeform, with their associate research

establishments.

In the near future Enrico believes his system will be marketed toward outdoor furniture,

bathroom modules and curved cladding, all of which have been demonstrated by

34.


D-Shape already. But the system is still costly; nearly £2000/tonne including operating

and development costs, yet in the future one would hope this becomes more competitive

and nears the quoted £750/t. Much of which is labour costs as the materials alone are

£175/t, so if the system becomes more accurate, there will be an associated saving in

the amount of after work that is necessary for a commercial product. Enrico is well

aware of this and mentions D-Shape “cannot match the cost of off-site construction right

now but they [Modern Methods of Construction] cannot produce freeform structures like

D-Shape”.

Enrico has been working on this technology since 2004, Freeform before 2006 and

Contour Crafting prior to 2001. Earlier research was carried out by Joseph Pegna in

1997, which demonstrated a similar use of blanketing sand deposition and selective

application of binder, per D-Shape, and perhaps could be accredited with the notion that

RP technologies could be used in the construction industry. He highlighted the

importance of building scale, in his research he calculated that to fully scale up existing

Fused Deposition technologies, individual beads of material would be 10mm in

circumference, not flat like D-Shape, he further concluded that whatever process is

developed must be able to deposit materials at construction rates (Pegna, 2007) and the

idea was developed still, where the latter must be a pre-requisite in addition to the

resolution of the smallest designed element, for functionality purposes (Soar R. , 2006).

These are the desired characteristics of a viable mega scale RP processes, but where

all three methods falter, is the combination of both these elements in the same

operation. Despite the need to use multiple materials, the primary operations are still to

be developed to their operating potential.

Here lies the crux, where is this technology heading?

35.

36

the future of mega scale Rapid Prototyping


5. Discussion

5.1. Drivers for change

It is being promoted by the Housing Forum that product availability will accelerate when

house designs are tailored to the requirements of manufacturing processes (Homing in

on Excellence, 2002). But why should this be so where, after all the clients themselves

are reportedly asking for more bespoke designs.

According to Gibb (2003) and with comparisons to off-site manufacture, the client is also

keen to improve; the construction and procurement time; quality of the finished product;

total cost to the client, and, productivity issues, in that order.

Yet using off-site manufacture the design freedom is somewhat hindered by the pre-

engineered nature of the modules or components, often box-like, inorganic structures.

In the past architects have been accused of not thinking about how products are going

to be made, and this is true of many concept designs which are increasingly being

abandoned because of cost. Professor Behrokh Khoshnevis found his own 30m x 10m

housing project scrapped because of the economic downturn (Pimlott, 2009). But where

investment can provide this step-change is with the intervention of government

legislation and funding of an equally grand scale.

Zero Carbon homes has definitely shown a change in the regulatory frameworks, which

could be a major factor for the investment in off-site production, yet this issue of

sustainability is a barrier that mega scale RP has to overcome. Vice versa, RP is not the

resultant of sustainable development; it is merely the means through which it may be

delivered.

5.2. Sustainability

For 20,000 years building has needed intense manual labour, so why is the industry still

facing problems such as low productivity, poor quality, low safety and a skilled labour

shortage? It is widely known that skilled labour in the UK is in short supply, which could

partly be the reason why the associated quality is one of the key drivers for the adoption

of new construction methods.

37.


Fig. 5.1: The Hummingbird/Sundance electrical generator, by Innovative Technologies Ltd.

By using automated construction, especially ‘Rapid Prototyping’ on site, construction

processes will ultimately entail further loss of unskilled labour in the industry, or, the

ability to not need to employ as many people on site. Mega Scale RP may however

provide more employment in the software development and hardware production

sectors, and it will invariably require operators to be qualified and/or trained to run the

software i.e. software engineers with a background in construction. So in regard to the

sustainability of personnel, by using mega scale RP employment will in fact decrease

on-site. And this itself raises issues of low-skilled jobs available to the economy, one

which the government will look upon unfavorably as this is the sector most closely linked

with unemployment (Pierrard, 2003).

But where there are reduced personnel, there is an inevitable reduction of injuries on

site. It is true that engineer’s build in safety factors (which may involve over-engineering

components) and I would stress at this point that this increases costs of materials. Yet

the issue is not added material in view of safety, it is the waste and amount of materials

being used. Environmentally concerned corporations continually address this idiom,

however it is the time it takes to construct the buildings that has a large affect on the

profitability of a project. Rt Hon Nick Raynsford stated after a government led MMC

initiative, that “an average of 13% of man hours on a project is wasted on non-value

activities” (McKeown, 2009), if this is reduced even by as much as half the savings

would be drastic.

Further to the above, RP systems use immense

amounts of energy and consequently running costs

are at a premium (Grimm T. , 2002). Similarly a mega

scale operation would also use a discernable amount

of said energy to power the automation, let alone the

high powered computer required to calculate printing

paths. But emerging technologies like ‘Free

Electricity’ can utilise the physical properties of

magnetic repulsion to rotate an electrical generator. This simple yet effective system

could be incorporated into the design and provide a truly sustainable machine. It would

therefore be the role of the materials technologist to provide the most ecological raw

product to further enhance the sustainable credentials of the system.

38.


5.3. Investment

5.3.1. Investment in the Construction Industry

Currently, in order to meet sophisticated clients needs, modular construction is being

used with common regularity, whereas previously ‘tried and tested’ methods were the

only course of action; however, modern trends seem to favour off-site production (Pan,

2005), whereby a bespoke production line (often robotically controlled systems) will

deliver a modular, ‘flat-pack’ assembly ready for fast on-site erection.

André Manseau’s book, Building Tomorrow (2005), shows the majority of innovations in

the construction industry are generally incremental and quantative data on innovation in

the construction industry is rare. Traditionally the construction industry is what some

may say impotent to change, even though it is generally agreed that there is a need for

more innovation. It is exacerbated by poor research and development efforts, just 0.3%

of turnover, compared to a staggering 10% of the pharmaceuticals industry, and the

majority of which originates from the supplier of the materials i.e. the use of CNC in the

steel industry, not the methods of construction, or the application of the materials

(Eurostat, 2000).

Most importantly of all is that the public and construction industry know very little about

Rapid Prototyping. The more the technology is used in architectural firms and the more

mega scale rapid manufacture is publicised, the lesser the animosity will be towards the

method and a greater chance for such technologies to be taken up by large construction

companies.

5.3.2. Investment in Mega Scale RP

The construction industry relies heavily on other industries to deliver new technologies,

and new products within the construction industry are not likely to appear without high

capital investment. Innovation can be costly, as all three case studies have shown their

dependence on research grants, so when there is so much interest in the systems from

large reputable companies, why do they not invest?

Commissioner for CABE, John Miles identified that “the parties who need convincing are

those being asked to risk their capital in transforming house building into a

manufacturing industry” (Abley, 2002). Speaking out at the Homing in on Excellence

39.


Conference, he continues that because of the secretive nature of R&D “it will continue to be

difficult to recoup initial investment in the current climate”.

The case studies have shown that printing a building in full or in component form is a long

way from being fully developed. Although additional research has been undertaken in

material properties, engineering of the components and reducing wastage etc., the issue is

delivering this on a scale suitable for construction.

This research, much like the investment from Enrico Dini was in the private sector, and it

should be put to the reader that the major driver for evolution is therefore governmental

investments and incentives. As minor investments incur naturally slow/small step changes,

which although they develop the process, the method takes and has been shown to take

decades to materialize as a common user product (Sedean, 1996).

5.4. Software

One of these minor step changes, which could have a big impact on providing a more

integrated client input to the design, is the use of so called black box software. This

seemingly invisible software can interact and modify the design to new calculated in addition

to engineered parameters of the structure, which could improve the client’s satisfaction. But

moreover in conjunction with mega scale RP, could offer self-build clients and any layman

for that matter, an opportunity to provide a structurally sound and individualised building

(Peters, 2010).

5.5. Designing the Future

The large benefit of using mega scale RP is its ability to realise almost any design

conceived, even for the most ambitious of architects as long as it is engineered properly it

should be buildable.

The only limitations of this technology in the future is the designers own ambition.

………………………… Lindsay Lucas: Technical Project Manager at Kingston Communications

By using mega scale RP nearly all architectural styles could be catered for, unlike other

methods of construction, yet similarly with most current building methods there are always

limitations to the design, whether it is material limitations or the buildability of the design.

Construction managers continually favour designs that are easy to construct, if the machines

are capable of printing the building in one operation, the machine would do this for them,

and hence items like jointing details need not be an issue.

40.


Fig. 5.2: Eda Yetis’ Hurricane House Prototype, produced by Selective Laser Sintering, highlighting the structural use, and the possibility of engineered buildings (Photo Taken at the Architectural Association Stand EcoBuild 2009)

Another point to raise is the affordability of the design. Off-site construction is generally

used in conjunction with associated economies of scale, or mass production. The

advantage of this is the product can be continually improved as the design team

becomes familiar with the system and can use any after sales knowledge to better the

cycles of manufacturing and design (Abley, 2002). But whereas modern methods of

construction may not be able to provide economic low-volume production, the

mechanism for virtual prototyping and physical printing of a one-off building, could

increase the design flexibility, productivity (Hopkinson N. &., 2006) and hence introduce

a mechanism for economies of small-scale production.

The majority of current off-site manufacture can only produce buildings and components

consisting of flat panels, however what happens if you wish to manufacture more

organic structures. You could make it from numerous flat sections arranged in a way

that creates curves. But architects today are increasingly moving away from the box

shapes and looking into more fluid forms like Eda Yetis’ Hurricane House (fig. 5.2).

These types of structures are

self-supporting (modeled

using SLS), offer vast

spaces within, and are very

complex in their make-up.

This sort of design could be

incorporated into Mega

Scale RP, as it is possible to

do it on a macro scale

already, illustrated in fig. 5.2.

If the same material where to

be used for the up-scaled

operation it should be feasible to assume that the building could withstand the same

scalar structural forces as per the macro version.

In view of EcoBuild 2009, No method of construction so far can offer fast production of this

form of construction and that is possibly why it is not a reality yet. But architects are used to

using and adopting 3D modeling, whereas construction operatives are only just realising the

potential of this software and are warming to the use of systems like BIM (Madsen, 2008).

41.


5.5.1. Archineering

“The new language (or style) of architecture seems to be based upon the adoption of a

new generation of 3D modeling tools” (Schumacher, 2004), Zaha Hadid’s partner, Patrik

Schumacher goes on to mention how the use of CAD was keenly taken up to support

the ambitious ideas of the designer as it allowed new levels of structural complexity,

fluidity and plastic articulation previously very difficult to draw and engineer.

With today’s knowledge virtually anything can be built, but if some elaborate structure is

preferred the client must be willing to bear the detrimental aspects of his/her aspirations,

namely the programme, quality, cost and possibly safety (Corus, 2007). And with

current practice architects often have to be restrained from creating something too

oblique otherwise engineering the structure cost-effectively would be near impossible, as

a result designers must only design that which can be built using existing methods.

If architects intend to use mega scale rapid prototyping as a construction method there

is little reason why they cannot produce elaborate buildings. However the primary

designer’s role may change to include greater engineering capabilities, resulting from

the lack of intermediacy between design and construction. Consequently for the

purpose of this paper these design personnel will be coined Archineers, and because

there is no possibility of post design changes once the print is under way; the designed

building must therefore be ready to build upon completion of the design. So due to the

irreversible nature of the construction method, design must be absolute and final upon

handover to the construction team.

5.6. Materials, Methods and Integration

Increased responsibility at the design stages also encompasses greater opportunities to

maximise efficient innovative space solutions, yet by examining the case studies it was

clear to see the potential of this is still yet to be fully realised.

5.6.1. Integrating two Materials

In essence there are three major materials used in construction, dense/load bearing,

plastics and metals. It was shown that producing a smooth transition between different

materials is near impossible with current methods, yet if the material were to be pre-

mixed, per D-Shape, with three troughs of (a) Material A; (b) 50% Material A – 50%

Material B; and (c) purely Material B. These materials could be deposited in sequence

42.


Fig. 5.3: Typical cross section of a wall (A) and a comparison of an impressionistic view (B) of the capabilities using mega scale RP (image courtesy of Loughborough University)

Fig. 5.4: Fused deposition systems. This particular example is a Fused Metal Deposition. Note the air stream and melt pool (images courtesy of Trumpf and Hopkinson, 2006)

difficult

mixing of compounds and grading

between the two a simpler operation.

where the integration occurs, but in addition the CAD model would not necessarily need

to define the different printing characteristics as the mechanisation and operation is the

same. These may be retrospectively coloured separately in the modeling stages, but

the automation software for the binding agent need not recognise the significance of the

separate material. Therefore this issue could be technological rather than a software

issue, which is defined by Hopkinson et al. (2006) as being one of the major barriers for

dual material grading.

However where Hopkinson has not conceded that to achieve optimised components like

those designed by Loughborough (fig. 5.3), the process may need to involve deposition

methods i.e. FDM, rather than the previously tested Laser Sintering.

The major advantage of using a deposition method over powder blanketing operations is the

ability to create voids without any un-sintered powder filling said voids. There are two

emerging technologies that look the more likely to provide this technique, namely High-

Viscosity Jetting and Fused Deposition (fig. 5.4). The latter offers a powder-based

process, but unlike other powder

systems, this jets the material into a

melt pool, and where paste systems

may find integrating materials

difficult, this system could find the

43.


Fig. 5.5: Multi-axis Robotic arm using Contour Crafting techniques. It shows that Contour Crafting has considered using a robotic arm, but developing such a system in the first instance would be very expensive, hence alternatives have been sought. (Image courtesy of CRAFT).

5.6.2. The Operating Mechanisms

There is a possibility of moving printer heads not only in the x,y,z axes, but in the

elevation plane, printing cantilevers, beams and arches could thence be possible without

the necessity of formwork, so long as the materials have sufficient stiffness and a good

mechanical bond to overcome the effects of gravity.

By making use of 5/7 axis robotic arms these elements could be easily produced as the

arm can manoeuvre in several planes at once. Yet the limitation is that there would be

far fewer printer heads when using this system, hence slowing the construction process.

Unless either several of these were used at once (expensive), or only one was

employed to produce just these elements alone, and a standard 3-axis rig to produce the

rest of the building.

The likelihood of integrating both a rig and robotic

arm at once is very slim at present as the two

systems are both complex in their own right, but

combining the two would involve years of research

and development, that would probably come after

either one type is commonplace on the market.

Enrico Dini estimated this to include 100 extra

employees. Consequently automation should be

kept as simple as possible, and the best solution

at present would be the 3-axis rig, which all three

of the mega scale rapid manufacture research

groups are using.

Robotic arms would favour the paste layering systems of Freeform and Contour Crafting

and high viscosity jetting, but as ecologist Colin Baker states, “the most prosaic things in

automation are the things that may trip you up” and robotic arms are no exception

(Baker, 2009). The previous and most prolific use of robotic arms is in the car

manufacturing industry, however they are not necessarily free-moving machines. Once

the robot is placed in a position where it may weld or do otherwise; it learns this and

then returns to its original resting position. The movements are all therefore pre-

planned, and thus the associated computer coding cannot be used for different

movements, necessitating the development of new movement algorithms (Dini, 2009).

44.


Fig. 5.6: Hexapod System by NIST. A surprisingly accurate CNC system which can tilt the head of the mechanical head, albeit to a limited degree, however it offers a versatility far greater than standard gantry sytems (Image courtesy of National Institute of Standards and Technology, USA).

It has been suggested that a gantry system like all three methods was expensive and

wasteful in resources, and could be construed as slow to erect unlike a hexapod system

(Lipkowitz, 2006). RoboCrane is one such area Contour Crafting is looking into, and

operates in a similar fashion to cable operated cameras as seen in many stadiums

around the world. But the future use externally, may be an issue as the crane is

suspended on wires that have proven unreliable in terms of stability where winds

increase the tension in the cables, consequently an inaccuracy occurs at the foci of the

camera. This is compensated by extra stabalising equipment, however this may not be

possible with a printer nozzle as the stabalising equipment cannot eradicate all jerky

movements so inaccuracies will inevitably occur. On screen this is alleviated by

switching to a different camera perspective however when printing a building the

equipment would need to be 100% reliable, with little or no flaws in the accuracy of the

automated movement. A more suitable application would be to use hydraulic arms (fig.

5.6) or roller screws, which would extend and contract the arms according to the position

required for material deposition. However it can be seen that this rig would be just as

complicated and expensive as the gantry approaches to manufacturing.

45.


5.7. Acting on the Drivers for Change

Some people whom were interviewed did offer some animosity toward the idea of

printed structures. It must be said that robotics in construction was heavily researched

by the Japanese during the 1990’s, to varying degrees of success. It was with this in

mind that Nick Nisbet, of AE3C, speaking at EcoBuild (2009), mentioned that “there is

not a lot of enthusiasm about robotics on site...this area is nothing new and was seen as

a gracious failure by the media in Japan”. His and many other personnel in the industry

are looking toward the use of robotics in factory conditions. He similarly mentioned that

it would be detrimental to leave an expensive machine out in harsh conditions where

another system under cover could produce the same building in better working

conditions, without the problems associated with high winds, driving rain etc. However

interestingly, he did note that if the system could do away with scaffolding completely

this would be a “big gain”, but would only become prevalent if value supports the use of

this system.

5.7.1. Quality-Cost Correlation

Automation of off-site manufacturing has improved upon both quality and the cost

implications; some may even go far as to say it has now become the standard to model

all other processes against (Baker, 2009). This is most relevant in the production of steel

structures, where the manufacturing processes’ are often computer numeric controlled

(CNC), and hence offer a controlling mechanism for factory tolerances. The graph

below however shows the relationship between achieving this greater accuracy and cost.

It shows that the lesser

the tolerances, the

greater the cost of site

production through extra

work. D-Shape is also is

suffering from this, but

surely if all, or most

elements are produced

using the same

technique, supply-demand curves would suggest, the more times you use a system (like

robotics, which can achieve high accuracy), the running cost will reduce. So it may be

Fig. 5.7: The influence of dimensional accuracy on steel structures v. cost calculation (image courtesy of Urbanska-Gaewska, 2008)

46.


Fig. 5.8: Freeform wall construction cost comparison (Image courtesy of Buswell, R.A. et al., 2007).

Fig. 5.9: Comparison of Freeform Construction v. traditional construction: time to completion of a wall section (Image courtesy of Buswell, R.A. et al., 2007).

the opinion that if high tolerances are required, and they invariably are, robotics is the

best method of producing such results, cost-effectively.

It is unfortunate that all three case studies shown are still currently very expensive

processes. It is true that material costs are still high, but what the massive research

investments toward Loughborough University

(£3.8m+) have shown that this process is still

being explored in regard to its niche, let alone

its development. As part of Loughborough’s

Freeform exploratory study they simulated a

scaled version of a Z-Corporation

machine this showed itself to be more

beneficial than traditional wall construction

techniques in terms of cost and speed and is

illustrated by fig. 5.9 & 5.10 consecutively.

5.7.2. Speed

Rapid manufacture is not necessarily

concerned with hastening the manufacture

process. The name is actually a misnomer

conceived for marketing purposes, but the

elimination of any tooling does in fact reduce

the time to manufacture a prototype object,

much like a one-off building. However figure

5.10 emphasises that this is only of a large

benefit where very detailed sections are

produced. And it must be noted that traditional

large walls are not necessarily high detail items, thus speed may therefore be unaffected

by the elimination of tooling for these components.

If a wall or building element were to be of enhanced detail i.e. insulation and wall

thicknesses were changed in relation to required performances, or the wall was an

organic form; rapid manufacture techniques may then prove beneficial for the project

delivery time.

47.


The reduction in construction time is possibly one of the most attractive aspects to a

contractor. And when comparing the speed of the mega scale RP process’, Contour

Crafting outshines its competitors for the rate at which a structure could be built, where

more representative methods of RP i.e. D-Shape and FreeForm, suffer from slower build

speeds. RP is largely constrained by the printing area, and much the same could be

said about the printing area of the latter two, but where Contour Crafting is largely

unrestrained in terms of printing area, its speed and deposition thus far does not deliver

an air tight structure. Consequently any sustainable credentials in regard to energy

usage and daily performance cannot compete against existing building techniques

(Kwon, 2002).

5.7.3. Quality

The same process has exhibited some development problems in terms of the binary on-

off nature of the extrusion path. D-shape shows a similar lag time between the software

and the shut-off valve of the liquid, consequently both systems work best in continuous

printing motions, however where this will become a distinct disadvantage for the integrity

of the structure, is the edge detail of the components.

Once again for CC, the trowels, which smooth the outer edges of the concrete, do offer

a solution to the external and internal surfaces. However where the nozzles are

required stop and start, before and after an opening, like a doorway or a window, the

surfaces adjacent to these components will be unfinished, and one would assume that in

modern methods of construction these elements are very weather/air-tight. Yet the

processes shown by D-shape and CC offer neither of these qualities. Much the different

could be said for FreeForm’s approach, as the research institute is focusing on using

existing RP techniques such as deposition and even new approaches like high viscosity

jetting. Which have shown on a macro level to offer the high levels of edge definition

and resolution that is required for integrating modern active and passive systems, like air

thermo-siphoning (stack effect) trunking, HVAC and light tubes etc.

5.7.4. Design Freedom

From an engineers perspective Jalal El-Ali, of Buro Happold said the “main interest is

making structures more efficient by controlling the amount and distribution of material in

the structure according to its needs” (2007). He continues “we have the knowledge to

design such buildings, we just need the tool”.

48.


The major advantage for rapid prototyping, yet the major disadvantage of Contour

Crafting is the degree of architectural freedom. CRAFT have shown themselves capable

of producing walls, however these are largely only in the vertical or near vertical; the

exception to this is the ability to produce domed sections. However this seemingly

archaen approach may not suit the architects who are actively following, and have a

vested interest in the project, like Xavier Dekeste of Foster and Partners, and similarly

Gehry Technologies (Pimlott, 2009). As Dr. Khoshnevis stated, “Architects are the

strongest advocates of this technology” (Mudholker, 2006), so a process, which does not

restrict/limit their design intuition should be a priority for mega scale rapid manufacture.

It was shown that the less radical approaches to mega scale RP i.e. Loughborough

Universities Freeform and D-shape, demonstrated that architectural styles and highly

engineered components could be catered for, thus geometrical optimisation was a

distinct possibility and similarly the use of material is easily reduced, hence providing a

more sustainable part. In the case of D-shape this has been proven with structurally

engineered stone and a structure has been built which most likely couldn’t have been

produced by any other means without huge expense.

It is because of this skin and core strategy, akin to many RP processes, those new self-

supporting geometrical forms like Eda Yetis’ Hurricane House could become

commonplace in our society, but the technology can also accommodate more classical

avant-garde Gaudi designs without a major team of stonemasons. It could even provide

a viable option for restoration projects, where plaster roses are difficult to replicate and

damaged gargoyles on the extremities of religious buildings are equally challenging and

time consuming to reproduce.

For this reason Mega Scale has a future application in the industry. In collaboration with

black box software it also has the potential to provide clients with the tool to build previously

unthinkable designs. Moreover by exploiting operational parameters and characteristics,

automated construction can provide integration and increased functionality above and

beyond existing construction capabilities. Further still RP is proving itself to be one of

the drivers for material diversity, like compressive (spongy) structures, gels, fabrics and

solids, although much of this is impractical on a mega scale due to the time consuming

nature of micro fabrication. Nevertheless it does highlight the range of possibilities that

Mega Scale operations could be providing to the industry in the coming future.

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5.8. The Future of Mega Scale RP in construction

The ultimate goal for Mega Scale construction was highlighted earlier as a process that

must be able to deposit materials at construction rates, but also one that incorporates

the resolution of the smallest designed element.

In ideal circumstances a perfected system would utilise the speed of Contour Crafting

paste layering system for the main structure, but for pipes, services and cantilever

sections, Fused Deposition or High-Viscosity Jetting is favoured as it can offer good

quality ‘tight’ structures. In reflection both systems would preferably act in unison, and

this would ultimately require the Fused Deposition or Jetting to speed up, or vice versa,

the paste layering should slow down. Seen, as the latter is more the likely it would be

deemed that the speed of a multi-material process would be inhibited by the same

method that could provide the detailed elements necessary for a fully functioning

building upon completion of the printing action.

It should be noted that in order to produce structures that offer true spatial and

topological optimisation, powder-blanketing operations are likely to hinder the design

process rather than benefit it. Aerated structures or honeycomb structures which in

construction have proven themselves to be very light yet strong functional

arrangements, may only be possible through material additive processes. Consequently

particular research and investment ought to be forwarded into the speed of these

processes, should this state-of-the-art construction method become a feature in modern

day construction.

Climatic variation could be accommodated by the use of off-site construction and unlike

current off-site methods, curved panels with different wall thicknesses could be

produced. Likewise off-site manufacturing could also provide a better quality product as

a result of these factory tolerances that may otherwise be affected by external factors.

This purports the necessity to manufacture components or sections of the building as no

feasible transport system could deliver a complete building economically. But to fully

maximise the logistical implications, these panels should also be in accordance with

standardised lorry widths and lengths (Royal Haulage Association suggests 3m x 12m

as a typical value).

50.


Energy shortages may also be accommodated in the design, but also off-site processes

could utilise technologies like Free Electricity, as illustrated in this paper.

Skills shortages would be dealt with, as the automated nature of the process will use

fewer workers in total, but more skilled labour. Which is a tough political prospect,

whether this could be construed as a positive, is possibly yet another area for research,

but one which could provide an insight into the extent of the barriers to innovation.

One area where this process will benefit all is the reduction of waste. The system uses

less material as a result of its design characteristics, but on a similar subject could

integrate immerging underground waste management technologies, like that of EnVac

(see appendix), into the actual structure, or even individual rooms if necessary.

Tension structures may also only be possible with the correct support for the extrudate

or similar to be printed upon. Rapid prototyping machines have previously been able to

produce cantilevers and spans by using water-soluble printed formwork. This may be

useful for producing doorways and such like, but like smaller machines, it will require a

lot of messy after-work to the structure. But it has been proven time again by D-Shape

that after work increases the final cost, thus this is another area for consideration of

future research. Further areas to note are:

1. Integration of Two Platforms, where robotic arms much like a human arm can

access very tight spaces, and a more traditional gantry rig collaborate.

2. Integration of Two Materials on a Mega Scale, and;

3. Non-Cartesian Robotics (free thinking nano-bots)

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6. Conclusion: the Direction This Technology is Heading

Although this process has the potential to deliver on so many drivers for change, the fact of

the matter is, it will not be able to do so in the near future unless the correct funding and

research is applied to these technologies.

However it would appear that there are two different directions which mega scale rapid

prototyping is heading toward. Firstly the process of Contour Crafting uses the extrusion

process to build the envelope, whilst using several robotic applications to deliver the modular

floors, services et al. in a specific manner that will allow the extrusion process to be a

continuous operation until the entire structure of the building is completed.

Secondly, both D-shape and FreeForm offer more conventional modular delivery systems.

Either by having an on-site factory based system or an off-site production plant, as seen in

many modern methods of construction. Loughborough’s own research has examined the

two of these options and concluded the use of off-site manufacturing was more attractive to

clients because of the space advantages it gives the clients and contractors at their

particular site, and it should be this method, which also uses common user plant, logistics

etc. that is recommended for use with mega scale RP construction.

This paper agrees with the above statement, as this has the added advantage to get rid of

any superfluous protection against the elements. Contour Crafting would most likely need

an exterior cover to allow operations to work in conjunction with adverse weather, however

where components are built in factory conditions, construction could remain unharmed and

untainted by what is happening externally. Moreover where the use of powder systems are

necessary, for instance Fused Metal Deposition; this powder and the inert gasses required

to build the material in the melt pool will not be affected, thus the quality of the final product

should remain high.

Obviously if this could be replicated on site it would provide enormous benefits in material

supply, logistics, and continuity of the building fabric. But one must note by building an

envelope of such grandeur prior to construction, this defeats the object of printing a building

in the first instance.

Referring to the title of this paper, it could be said that this process is not in fact an evolution

as such, but a development of existing ideas. It was shown by academics at Loughborough

University that in the near future the system is likely to be used in a similar fashion and even

53.


There are still material and technological barriers to overcome before this method can

become more widespread, much of which has been highlighted in this paper. But once

these have been fully developed, off-site Mega Scale Rapid Prototyping could become

commonplace and is likely to deliver a new process for the digital age of construction.

in competition with off-site manufacturing. The key advantage in this respect, is the

geometrical benefits that modular units cannot address, as these are largely pre-engineered

units, which principally become cost effective due to the limited structural design required at

the procurement stages.

Because of ‘black box’ software, mega scale RP can offer the same level of procurement

savings, but where off-site construction reduces the supply-chains, mega scale RP would

reduce this further to only a few major material suppliers.

So by manufacturing the building using RP the current off-site manufacturing methods could

quickly become outdated and could offer an easy transition for construction managers and

clients alike. The similarity of the management structure to off-site construction would prove

beneficial for those in the industry who may prove impassive to change, but moreover would

allow other mechanisms like logistical transportation, and even site plant to easily adapt to

the new structures that could be delivered.

It is true that the aim of contour crafting is to build/print a structure in its entirety and this may

be of great benefit if geometrical limitations are addressed, but out of the three methods

examined, it is the only one which is carving its own niche, whereas both D-shape and

Freeform offer solutions as site factories or off-site construction plants.

Contour crafting still uses modular elements to enhance the speed of construction, but the

common trend of all the research institutes is the integration of the functional components

within the fabric of the structure.

The ability to offer new architectural possibilities will be the major driver for this method, and

it is for this reason, which stands out over and above the rest, that Mega Scale Rapid

Prototyping will indeed become the future of manufacturing.

Yet investment at this stage is crucial, but it is the construction industry and government who

need to be convinced of this technology, not the architects, as the former are the ones who

are likely to risk their investment capital. Like Aristotle states, in his discussion on causation,

this is only likely to happen where “there is the goal or end in view, which animates all the

other determinant factors as the best they can attain to” (Physics II, iii; 195a 24-26).

54.

Bibliography

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68.

It must be noted that there has been several government parties who oppose the claims from the

proprietor of this technology. However one knows that using magnets which repel each other, it is

possible to rotate the non-static of the two. This alone gives an insight into the potential and illustrates

the point of this technology in a simplistic manner.

An Evolution in Construction

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